The present invention relates to temperature sensing devices and pertains particularly to an improved temperature probe for insertion into animal tissue.
During surgery on organs such as the heart, it is desirable to know the temperatures of the organ during this operation. Temperature sensors which are currently available are in the form of a stainless steel needle for insertion into the organ for sensing the internal temperature of the organ.
These presently available temperature sensors have a number of drawbacks. For example, due to the high thermal conductivity of stainless steel, heat is conducted very rapidly along the needle. The resultant temperature tends to indicate an average temperature over the length of the needle. This is undesirable in most instances in that it does not provide means for obtaining a reasonably accurate point location temperature nor an accurate temperature gradient measurement between spaced positions.
Another drawback to the stainless steel needle temperature sensor is the rigidity thereof. The stainless steel needle is reasonably rigid or stiff and when inserted into the organ tends to go through the muscle fibers rather than around them. This increases potential injury and trauma of such use.
The lack of flexibility of such needles also has a tendency to cause further injury if accidentally knocked out to the tissue. This is particularly so where side forces are placed on the needle. In such instances, the needle tends to rip the tissue.
The applicant has discovered that the needles can be made of certain plastics and thereby have certain advantages over stainless steel needles. Plastics according to the invention have lower thermal conductivity and thereby improved accuracy. The use of plastic also allows a certain flexibility in the needle that reduces tissue stress during probe use.
It is therefore desirable that a flexible stable probe for insertion into animal tissue for accurately sensing the temperature thereof at one or multiple positions during surgery be available.